[clang] [clang][modules-driver] Add dependency scan and dependency graph (PR #152770)

[Chuanqi Xu via cfe-commits]

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@@ -0,0 +1,112 @@
+//===- ModulesDriver.h - Driver managed module builds --------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file defines functionality to support driver managed builds for
+/// compilations which use Clang modules or standard C++20 named modules.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_DRIVER_MODULESDRIVER_H
+#define LLVM_CLANG_DRIVER_MODULESDRIVER_H
+
+#include "clang/Driver/Types.h"
+#include "llvm/Support/Error.h"
+
+namespace llvm {
+namespace vfs {
+class FileSystem;
+} // namespace vfs
+namespace opt {
+class Arg;
+} // namespace opt
+} // namespace llvm
+
+namespace clang {
+class DiagnosticsEngine;
+namespace driver {
+class Compilation;
+} // namespace driver
+} // namespace clang
+
+namespace clang::driver::modules {
+
+/// A list of inputs and their types for the given arguments.
+/// Identical to Driver::InputTy.
+using InputTy = std::pair<types::ID, const llvm::opt::Arg *>;
+
+/// A list of inputs and their types for the given arguments.
+/// Identical to Driver::InputList.
+using InputList = llvm::SmallVector<InputTy, 16>;
+
+/// Checks whether the -fmodules-driver feature should be implicitly enabled.
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ChuanqiXu9 wrote:

Can we avoid enabling it implicitly? I fear there will be more problems than helps. It is not complex to add `-fmodules-driver` for users. And after all, if we find this is really useful in practice, we can add the feature (enable it implicitly in different conditions) in another PR. It won't be late and hard.

https://github.com/llvm/llvm-project/pull/152770